Vincamine, one of the alkaloids from vinca minor L., is known to have vasodilative effects in the cerebral vessels. Many known derivatives of vincamine have been synthesized. The general structure of vincamine and vincaminic acid are as follows: ##STR3## When vincamine is administered to humans orally, intravenously or intramuscularly, it is hydrolyzed, mainly by liver esterase, to vincaminic acid which lacks activity and is excreted in the urine. The known derivatives of vincamine are alcohol esters of vincaminic acid which are readily hydrolyzed by liver esterase.